This invention relates to an electric discharge gas-dynamic laser and more particularly to an EDGDL operating on the 16.mu., (02.degree.0)-(01'0), and the 14.mu., (100)-(01'0), transitions of .sup.12 CO.sub.2.
Heretofore EDGDL have been set forth in "CWCO-CS.sub.2, CO-C.sub.2 H.sub.2 and CO-N.sub.2 O energy transfer lasers", by J. A. Stregack, B. L. Wexler and G. A. Hart in Applied Physics Letters, Vol. 28, No. 3, Feb. 1, 1976, pps 137-139, and "D.sub.2 -CO.sub.2 and D.sub.2 -N.sub.2 O electric discharge gas-dynamic lasers", by J. A. Stregack, B. L. Wexler and G. A. Hart in Applied Physics Letters, Vol. 27, No. 12, Dec. 15, 1975, pps 670-671.
The gas-dynamic laser and in particular, the electric discharge gas-dynamic laser (EDGDL) are established methods for the production of non-equilibrium states of a gas which are suitable for lasing. A gas in such a condition typically has one or more vibrational modes at a very high effective temperature, which other modes as well as the translational and rotational degrees of freedom are at very low temperatures. Lasing is possible in the hot modes, or between hot and cold modes, but the numerous desirable laser transitions in the cold modes remain inaccessible.
Optical pumping of molecular species is an even more selective technique for populating selected states of a molecule and has been used to produce IR and far-IR lasers. Optical pumping by itself has some fundamental limitations. Only states coupled to the ground state by IR-active transitions are accessible unless the gas is heated. Unfortunately, simple heating carries the danger of populating the lower laser level of the desired transition. Direct optical pumping is at best a one-for-one process: every pump photon absorbed will produce at most one lower-energy lasing photon, even in the absence of all relaxation and other processes. Thus, the pumped laser is only as scalable as the pumping laser.
The optically pumped gas-dynamic (OPGDL) laser has all the advantages of these two approaches, but many of the individual limitations of each technique are not present when combined. States not accessible by either approach individually can now be excited with a high degree of selectivity using the combined methods. Scalability of the pumping laser is not as severe a problem; in general, the thermal or electrical input to the GDL will provide the bulk of the energy. In the special case where the upper laser level of the OPGDL is unexcited by the GDL and is below the vibrational levels excited by the GDL, no photons are absorbed in the pumping process; rather, stimulated emission takes place and the pumping beam is amplified. Efficiency for pumping CO.sub.2 (001) in a GDL can be very high, promising high overall efficiencies.